By Dr. Karen Shaw Becker
Welcome to Cat Week, an entire week devoted to all things feline! Many of my Healthy Pets visitors have asked for more cat-centric videos and articles, so I decided to do a full week of interviews on a variety of feline-specific topics. I have a very special first guest for the week whose name will be familiar to veterinarians who are watching or reading here. It's Dr. Joseph Bartges of the University of Georgia (UGA) College of Veterinary Medicine.
Dr. Bartges is a world-renowned expert in veterinary internal medicine, specifically kidney and urinary issues in both dogs and cats. He's also a board-certified veterinary nutritionist. He's originally from West Virginia and graduated from Marshall University in Huntington.
Dr. Bartges attended veterinary school at UGA and completed his residencies, PhD and postdoctoral work at the University of Minnesota. In addition to UGA, Dr. Bartges has been on the faculty at the University of Tennessee College of Veterinary Medicine. He was also in private practice for a few years and taught at Cornell University.
At UGA, Dr. Bartges is Professor of Internal Medicine and Nutrition. "I teach several courses, as well as see patients on the clinic floor, and do research," he explains.
"The three arms of an academic position are teaching, research and service, so I'm involved with teaching students, health officers and general public veterinarians, research in different areas, and then service in terms of seeing patients, committee work and serving on editorial boards and things like that."
Dr. Bartges also does a lot of writing, including both scientific publications and review articles. Obviously, he has a very full plate, and I really appreciate that he's taking time to talk with us about cat health today, specifically dietary and urinary issues.
Why Cat Diets Should Include a Variety of Different Foods
My viewpoint, which I believe is also the viewpoint of the Association of Feline Practitioners (AAFP), is that cats do better with a moisture-rich diet. I'm a big advocate of feeding either canned food or nutritionally balanced fresh food. I asked Dr. Bartges what he would feed a new kitten he brought home.
"We actually have two kittens in our home that are getting close to a year of age," he replied. "They were feral. In our neighborhood, we trap feral cats and get them spayed or neutered. One of them was a queen who had three kittens. We were able to catch the kittens, found a home for one, and decided to keep the other two.
Our kittens eat a lot of different things. Twice a day, they get some canned food of different varieties, plus they nibble on dry food that's on a timed feeding system. They get lots of treats, and we also make a homemade mix of kale and chicken they get once a day. They also get canned sardines, mackerel, tuna or something else at night, as well as a raw egg with whole cream once a day."
Wow! I see why those kittens made the wise decision to hang out at Dr. Bartges house instead of the neighbor's! He's feeding them some processed food, fresh living foods and a tremendous variety of foods. I asked him how important he feels it is to offer cats, especially growing cats, nutritional diversity.
"I think it's really important," says Dr. Bartges. "There's not a lot of scientific data to back it up but I think it's important for them to eat a variety of foods. I think it does a couple of things. You want variety in textures, and you want variety in flavors. Cats tend to be good at getting locked into a food. And then if you need to change the food, it becomes a real headache or impossible.
By giving them a variety of things, again, it accomplishes two things. One is it gives them familiarity with lots of different textures. It's a mix of textures of commercially available canned and dry foods, as well as treats, plus homemade treats and foods.
The other advantage of a variety of foods is if, for example, there is a cat food, a group of foods, or a specific ingredient that has been recalled for some reason, when we offer a variety of foods, it dilutes that potential adverse effect down.
It also keeps them engaged. My cats are very interesting, because they're very lean, but they're very food-motivated. They know when that timer on the feeding system clicks every 16 hours. When that thing clicks, man, they are all over it because they get to nibble on dry food. They're willing to try different things."
Cats Fed a Nutritionally Diverse Diet Often Enjoy Trying New Foods
I have found the sooner you introduce nutritional diversity to kittens, the better, because it will be easier to get them to eat a variety of foods for the rest of their lives.
"We brought our kittens indoors when they were somewhere around 8 to 12 weeks old," explains Dr. Bartges. "We started the diversity in their diet fairly early and we've been able to expand on it.
These days, if we put something down, they're interested in trying it. If we get a new treat, they don't take their time getting used to it. They're usually right on top of it. We have these treats that look like twigs. I don't know what they're called, but they have like a woody consistency. They love those things!
We rotate their food and we don't feed growth diets. We feed them three kinds of diabetic diets that are high-protein, low-carb diets, and three types of critical care diets that are high-protein, high-fat, low-carb diets, both dry and canned. Every two days they get a different flavor, a different texture, a different everything."
I asked Dr. Bartges if he has any tips or tricks for diversifying the diet of an adult cat who's locked onto or addicted to a specific food.
"It can be tricky because cats are cats," says Dr. Bartges. "Mix the old and the new food together if possible, so that they can't pick it out. If you don't mix them well, cats are really good at picking out the old food and not touching the new. You can try adding a little water, which makes the foods easier to mix together. Or add flavored broth. If they're used to a chicken-based food, try using chicken broth to give the new food the flavor of chicken."
Dr. Bartges also uses interactive and food-dispensing toys to encourage the kittens to exert themselves and play games to get treats. He suggests getting your cat used to a new food by having her hunt for it. "Keeping them active and tapping into their hunting instinct can get them motivated to try something new," he explains.
Curing Kitty Boredom and Inactivity With an Indoor Exercise Protocol
My observation is most indoor-only cats are bored out of their minds. Napping is a big part of their day, but their nature is to be physically active. I asked Dr. Bartges for his thoughts on the relationship between environmental stressors and certain feline disorders like chronic cystitis.
"It's a little tough to prove or disprove," he replied, "but I think we're developing an appreciation for the need for environmental enrichment, and decreasing stress in general. And veterinary clinics are starting to adopt cat-friendly protocols as well.
As I mentioned, we keep our kittens active by having them hunt for food and using food puzzles. The male, Ray, is really good at this, figuring out how to get food out of something. They have vertical spaces they can climb or jump to. At night when they tend to be really active after eating, they can play with battery-operated toys that move around and make noise.
We also have a laser toy and they'll wear themselves out chasing that little red dot of light. Every night we do that with them so they stay active."
Dr. Bartges is intentionally creating an indoor exercise protocol for his cats, which is fabulous.
The Role of Moisture in Feline Diets
Next, I asked Dr. Bartges for his thoughts on how big a role moisture plays in feline urinary health, and his suggestions on how to increase moisture in a cat's diet.
"That's a good question because there's data on both sides of the argument," he answered. "Feral and wild cats eat small prey full of moisture and protein, minimal carbohydrates, and lots of bones. But that doesn't mean cats can't do fine eating other types of food.
We know from experience and from studies that adult cats have a wide safety margin. A lot of over-the-counter foods are designed for the average cat or average dog, so they're adequate. The real question is, can we do better than adequate? And is your pet an average pet?"
I've had cats that lived to be 20 on a dry diet. But moisture helps, because cats don't tend to drink a lot. My two kittens drink hardly any water because they get plenty of moisture in their canned and homemade diets. We put water down for them and freshen it every couple of days, but there's usually not much missing from it.
Young, healthy cats on dry diets don't tend to drink a lot. But as they get older and their kidney function starts declining or they're prone to diseases of the bladder — stones, crystals or whatever — their concentrated urine can become a problem. If they're not used to a moisture-rich diet, switching them to one is hard to do. That's why it's best to get them on a varied, moisture-rich diet as kittens."
Helping Kitties With Chronically Inflamed Bladders
Many of my Healthy Pets visitors have cats with inflamed, irritated bladders. I asked Dr. Bartges if there's anything new on the horizon — any new research, ideas, thoughts or tips — on helping kitties with chronic inflammatory conditions of the bladder.
"There are two primary theories," he explains. "One is a virus theory. There are some cats that probably do have viruses that attack only the bladder. And while we can diagnose these viruses, currently there's no treatment available.
The other theory involves what we call neurogenic inflammation. It's related to the ability of environmental stress to create inflammation. It occurs in utero to kittens of mother cats under stress. As the kittens get older, they aren't able to mount an appropriate stress response.
What happens is when we mount a stress response, there's a feedback loop that signals the body to turn it off or to dampen it to keep things in. There's some data to support that cats with the tendency mount a stress response, but they're not able to dampen it or shut it off.
The stress then targets something. It could be the bladder, so they develop bladder pain issues. It could be the intestines, so they develop inflammatory bowel disease. It could be the skin, so they pull their fur out. It's hard to predict what organ(s) will be targeted.
To address these issues, we start with environmental enrichment. And then there are some pharmacologic and non-pharmacologic ways of helping as well. There's a study that showed feeding a diet high in omega-3 fatty acids, antioxidants, and an anti-anxiety ingredient made from milk protein, helped decrease recurrence of bladder issues in cats.
We sometimes also use herbal preparations or extracts that provide a calming effect for clients who aren't sure they want to use drugs. It just depends on the patient's symptoms and what the owner wants to do."
I went to vet school 25 years ago, and at that time, we didn't have many options to help cats with chronic urinary tract disorders. I asked Dr. Bartges if he feels we've made any headway in the last decade or so.
"I went to vet school earlier than you did," he says, "and it's true, we didn't have a lot of options. We didn't fully understand the role of diet. With idiopathic disease (disease without a known cause), vets recommended solutions with no data whatsoever. Most cats get better in four to seven days, regardless of what we do. It's the kitties with recurrent or long-standing disease who don't have many options.
But around 2015, there was work done by certain veterinary researchers — Tony Buffington at Ohio State University, [Jodi] Westropp who's now at the University of California-Davis, John Kruger at Michigan State and others — that looked at viral causes and the role of stress, and developed some potential solutions.
I think a change in diet probably helps more often than not, as long as you're not inducing an additional stressor by trying to change the diet. I also think it's important to get involved with your cat, rather than only seeing him at mealtime. I think interacting with cats helps lower their stress level. Cats are solitary, but they also enjoy attention."
Omega-3s, Fish and Fish Oil Sources
Next I asked Dr. Barges how much omega-3 supplementation is necessary for cats eating a canned or dry commercial diet, because we know high heat processing destroys essential fatty acids.
"I think it depends on the source of the omega-3s," he replied. "A lot of foods have omega-3 fatty acids in them, but they're not coming from fish or marine life. Cats lack the ability to convert the omega-3s found in, say, flax seed oil, to the omega-3s needed to control inflammation.
Omega-3 supplements must contain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the two long-chain fatty acids. You want to give omega-3s sourced from marine life.
High heat processing is a problem, but so are plant sources of omega-3s, because cats can't use them effectively. A cat with an inflammatory condition who's eating a diet high in omega-3s may still need to be supplemented to achieve an anti-inflammatory dose."
A question I get regularly about feeding fish oil is, "But about the iodine, heavy metals, polychlorinated biphenyls (PCBs), dioxins and other contaminants?"
"Well, we feed our cats foods that are organic, non-GMO, antibiotic-free, and so forth. We feed a lot of canned fish products because they are labeled as not containing heavy metals. And there are studies that show canned sardines have indeed been checked for heavy metals, so we feel good about that.
When it comes to wild caught claims, it gets trickier unless someone has analyzed the fish and verified it's free of heavy metals and low in iodine. And in the case of iodine, it depends on the form of iodine.
For example, bananas have a lot of potassium, but we don't get a lot of potassium from them because it's bound. Bones contain a lot of calcium, but if you feed a raw bone, your pet doesn't actually get a lot of calcium because it's bound. So even though a food has a high amount of certain minerals, it doesn't mean we're assimilating all of those nutrients."
Are Commercial Pet Foods Formulated Correctly for Hyperthyroid Cats?
I have a theory that the high rate of hyperthyroidism we're seeing in cats today may be related to the use of synthetic iodine as an additive in commercial foods, whereas whole food iodine, which is what would be found in seafood, would be absorbed differently in cats' bodies. "Absorbed and utilized, absolutely," Dr. Bartges agrees.
There are commercial therapeutic diets available for hyperthyroid cats, but I asked Dr. Bartges if when we formulate custom diets for cats with hyperthyroidism, we should eliminate iodine.
"I wish I could say yes or no," he answered. "I think it depends on the organizations that make those decisions. You can't have zero iodine, because iodine deficiency causes its own problems. It's a matter of achieving a level. When it comes to homemade diets and iodine, I usually look at AAFCO (Association of American Feed Control Officials) profiles and decide how much I want to restrict it. When I get asked if the diet meets AAFCO standards, the answer is, not always.
AAFCO requirements are designed for healthy adult cats, growing kittens, or whatever, and I'm formulating a diet for a cat with hyperthyroidism.
The National Research Council (NRC) is the organization that sets minimums based on purified diet studies, whereas AAFCO sets levels of adequate nutrition for the four life stages for an average, healthy animal. Adequate nutrition isn't necessarily optimal nutrition, nor is it designed for a not-average dog or cat."
Are AAFCO's Life Stages Adequate for Every Pet?
"AAFCO recognizes four life stages: adult maintenance, pregnancy, lactation and growth," Dr. Bartges continues. "But you could really narrow them down to two stages — adult maintenance and reproduction — because pregnancy, lactation and growth look very similar.
The advantage of an all-life stages diet for people looking for convenience is you can feed it to a kitten or a puppy, and then as they become adults, you can just continue to feed the same food.
One of the problems, though, is an adult maintenance nutrient profile is the same for a 1-year-old Chihuahua and a 15-year-old Great Dane, or a 2-year-old domestic shorthair cat and an 18-year old British Blue. They probably need different profiles. We know there are differences across age, and certainly probably differences between a Chihuahua and a Great Dane.
I think the issue is that it's too hard to come up with a set of nutrient profiles that are very specific, and make those the standard. I think that's what the regulatory side has problems with. I think it's what pet food companies are going to have problems with.
The way I look at this is sort of like the food pyramid. If I built a food pyramid, I would put a homemade diet at the top, because with a homemade diet, I have complete control over the ingredients. I can make it with simple, limited, fresh, whole ingredients, and I can make changes easily.
Next would be therapeutic diets because there's more quality control. These are more defined formulas, and although they're defined for specific diseases, some of them are okay to feed for growth or pregnancy or adult maintenance. For example, we use a lot of joint diets for puppies because they're high in omega-3s. They contain omega-3s above and beyond the average profile.
Below therapeutic diets I'd put life stage-specific, so growth for growth, adult for adult. Below that, I would put all-life stages, at the very bottom."
I love that Dr. Bartges feeds safe fish to his cats, and raw eggs. I asked him if there are any other foods he would suggest we offer to healthy cats to improve microbiome health and nutritional diversity.
"We actually give them a probiotic too," he replied. "I'm a big believer in probiotics. Rotating foods is also a good idea to prevent your cat from getting locked into only one food. Provide variety every day or every other day, not every six months, because six months is long enough for them to lock in."
Can We Prevent Kidney Disease in Today's Cats?
I have one last question about kidney health for Dr. Bartges. I want to know if he has any tips or tricks for owners of cats with kidney disease, or to prevent kidney disease. It seems to be a weak link in domestic cats.
"If I found the answer to that, I would be retired," he says. "It's kind of interesting that one of the things we do is restrict dietary protein in an animal that eats a lot of protein. Why would an animal who's used to eating a lot of protein develop a disease where you'd want to restrict the protein?
Is there something we can do to prevent it? Unfortunately, at least at this point in time, we really don't know. There have been some theories about the role of viruses in vaccines that hasn't really been expanded on. We don't know if it plays a role or not.
Is there something in the diet that causes it? Nobody has found one or more things. Certainly, eating high protein doesn't cause it. Cats are carnivores. They're high-protein eaters anyway. But even in humans, a high-protein diet doesn't cause kidney disease.
What happens when a cat develops kidney disease is they lose some function, and the body compensates. And then they lose more function through compensation, until they finally reach the point where there is no more compensation available. That's when the lab numbers go up, and their overall health starts to decline. At that point we try to minimize the excesses and deficiencies that occur with abnormal kidney function.
There are new biomarkers available for earlier detection of kidney disease, but we're still working through the best way to use them. I think there's a role for them, but I still have situations where I look at the numbers and think, 'That doesn't make sense.'"
Suggestions for Cat Parents Concerned About Kidney Disease
Dr. Lisa Pierson, whose interview will be coming up later in the week, believes if you've been through the heartbreak of dealing with a cat with kidney disease, you never get over it. We have a lot of clients with new cats who say "I can't bear to go through this again. I want to check early on." Dr. Pierson shows her clients how to check urine specific gravity at home. I asked Dr. Bartges his thoughts on how often we should check, and how early.
"Well, you're going to get a different answer from different people," he explained. "With the dogs we've had in the past and the cats we have now, we do their kitten vaccines. They're coming up on one year of age and will get their boosters. After that, we'll do vaccine titers.
I would rather spend my money on annual exams and picking up changes and trends in bloodwork over time, than vaccinating. Now you're kind of locked into rabies because of the legality and the zoonotic potential. But the other vaccines, if you measure titers, a lot of them maintain a high antibody titer. They don't necessarily require revaccination.
I think getting baseline lab work at  to  or  years of age, somewhere in that range, is a good idea. When it comes to checking urine specific gravity at home, there was actually a study that looked at adult cats and kittens. The majority of adult cats and kittens have urine specific gravities above 1.035, regardless of the time of day.
You could argue it's a good sign because they're concentrating urine, but you could also argue they're actually dehydrated, which could be a trigger for kidney problems. I know our cats have numbers under 1.035 because they get so much moisture in their food. I think measuring urine specific gravity is a good idea as long as you keep the cat's diet and your overall goals in mind.
If a cat is on a low-moisture diet, then a 1.060 specific gravity is normal. But maybe that's not a good thing for a cat in the long run. If they're on high-moisture foods, a 1.030 or a 1.025 might be abnormal, because most cats concentrate better than that, but that might be a good thing because it's keeping the kidneys diluted and flushed out.
I think, instead, looking at bloodwork and looking at it over time is the important thing, especially for pet owners who have had animals with kidney disease. I would tell them, 'Start young and look at, especially, where the creatinine is.' If you trend creatinine over time, it gives you good information, as long as the kitty is hydrated when the samples are taken.
If their creatinine is 0.9 year after year after year, then when they get to be 12 it goes to 1.1, and then to 1.3, it's still in the normal range, but the trend is going up. That might be the time to intervene. Whether it helps or not, we don't know yet. But it probably can't hurt."
Moving Toward a More Proactive Approach to Veterinary Medicine
I think it's important to be proactive and know those changes are occurring. It's better emotionally for cat parents than suddenly being told their pet is in kidney failure. That can be devastating.
"Veterinarians have traditionally been trained to be reactive with diseases and proactive with infectious diseases," Dr. Bartges points out. "We're trained to use anti-parasite drugs, flea control, vaccines and all that, but we're not trained on how to intervene to prevent a disease from occurring in a high-risk situation. I do think recently we've started moving more toward prevention, however.
We use therapeutic diets as a preventative in healthy animals if they have a high risk for a certain disease. If you have a cat who's prone to urinary stones, feeding a diet that might help lower that risk, especially if it's a good food that can be offered on a maintenance basis, is a win. We've been doing much more of that type of thing for the last [five] to 10 years."
Dr. Bartges is a role model for others in our profession in moving from a reactive to a proactive practice model. Through his teaching, his approach is being offered to future generations of veterinarians who will have a different perspective than we did coming out of veterinary school.
"It's not just about acquiring knowledge," agrees Dr. Bartges. "It's about acquiring wisdom. I hope there is some wisdom in that approach." I very much appreciate Dr. Bartges for sharing his time and wisdom with us today.